Abstract

2-Nitroaryldifurylmethanes 1a and 1b, readily available by condensation of 2-nitrobenzaldehyde and 6-nitroveratraldehyde with 2-methylfuran, were transformed into indole, cinnoline and benzothiazine-3,1 derivatives. The reduction of 2-nitroaryldifurylmethanes gave the corresponding anilines 2a,b or indole 3 depending on the reaction conditions. A plausible mechanism for the last reaction involving intramolecular heterocyclic addition between a nitroso-group and a furan ring is proposed. Diazotisation of the amine 2b gave a cinnoline derivative - a product of intramolecular oxidative furan ring opening. Treatment of isothiocyanates 7a,b with perchloric acid resulted in a new rearrangement with furan ring migration leading to the 4-Hbenzothiazine-3,1 derivatives.
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